Fuel cells for catalytically combining elemental hydrogen and oxygen to generate electricity are well known. In so-called proton exchange membrane (PEM) fuel cells, the protons migrate through a membrane and combine with oxygen at a cathode. In so-called solid oxide fuel cells (SOFC), oxygen anions migrate through a solid oxide electrolyte layer and combine with hydrogen at an anode. In both types of fuel cells, gaseous hydrogen is provided to the anode surface. A common means for forming hydrogen in fuel cell systems is through catalytic partial oxidation (known in the art as “reforming”) of hydrocarbons such as gasoline via the following non-balanced equation:CnHn+2+O2=>H2+CO  (Eq. 1)A PEM fuel cell is intolerant of CO, which can be removed in known fashion. An SOFC can utilize both H2 and CO as fuel sources, being oxidized to H2O and CO2, respectively.
A potential problem exists is providing hydrogen via a catalytic reformer in line with either type of fuel cell. As a reformer ages in use, the catalyst tends to become less efficient, and the reformate stream may contain a small percentage of non-reformed hydrocarbons. Fuel cell anodes are sensitive to the presence of hydrocarbons, which are readily converted to graphitic carbon, poisoning the catalytic sites of the anode. It can be costly, inconvenient, and time-consuming to replace or regenerate the poisoned anodes in a fuel cell stack.
What is needed in the art is a means for monitoring the gaseous output of a fuel cell reformer to determine when reformer inefficiency becomes a danger to the health of the fuel cell anodes.
It is a principal object of the present invention to prevent significant anode poisoning in a fuel cell system by monitoring and alarming hydrocarbon levels in reformate being provided to the fuel cell system.